Collection Operations क्या हैं

Collection operations तैयार-बनी recipes हैं, जैसे sort या find, जो Kotlin आपको देता है ताकि आपको आम कामों के लिए loops न लिखने पड़ें।

In this page:

Sorting a Collection
Searching with find, any, all, none
Counting and Summing
Grouping Elements

Syntax

kotlin

list.sorted()
list.sortedDescending()
list.find { condition }
list.any { condition }
list.all { condition }
list.count { condition }
list.sum()

Sorting a Collection

.sorted() ascending natural order में elements वाली एक नई list return करता है, जबकि .sortedDescending() उन्हें descending order में return करता है -- कोई भी original list को modify नहीं करता।

उदाहरण: Sorting a Collection

markup

// Entry point: execution of the program starts here
fun main() {
    // Declare a read-only variable `numbers`, set to `listOf(5, 2, 8, 1)`
    val numbers = listOf(5, 2, 8, 1)
    // Print "Sorted: ${numbers.sorted()}" to the console, with a trailing newline
    println("Sorted: ${numbers.sorted()}")
    // Print "Descending: ${numbers.sortedDescending()}" to the console, with a trailing newline
    println("Descending: ${numbers.sortedDescending()}")
}

Searching with find, any, all, none

.find { predicate } किसी condition से मेल खाने वाला पहला element (या null) return करता है, जबकि .any, .all, और .none जांचते हैं कि क्रमशः कुछ, हर, या कोई element condition satisfy करता है या नहीं।

उदाहरण: Searching with find, any, all, none

markup

// Entry point: execution of the program starts here
fun main() {
    // Declare a read-only variable `numbers`, set to `listOf(1, 2, 3, 4, 5)`
    val numbers = listOf(1, 2, 3, 4, 5)
    // Print "First even: ${numbers.find { it % 2 == 0 }}" to the console, with a trailing newline
    println("First even: ${numbers.find { it % 2 == 0 }}")
    // Print "Any negative: ${numbers.any { it < 0 }}" to the console, with a trailing newline
    println("Any negative: ${numbers.any { it < 0 }}")
    // Print "All positive: ${numbers.all { it > 0 }}" to the console, with a trailing newline
    println("All positive: ${numbers.all { it > 0 }}")
}

Counting and Summing

.count { predicate } गिनता है कि कितने elements किसी condition को satisfy करते हैं, जबकि .sum() numbers के किसी collection को सीधे जोड़ता है और .sumBy { } हर element से एक computed Int value sum करता है।

उदाहरण: Counting and Summing

markup

// Entry point: execution of the program starts here
fun main() {
    // Declare a read-only variable `numbers`, set to `listOf(1, 2, 3, 4, 5, 6)`
    val numbers = listOf(1, 2, 3, 4, 5, 6)
    // Print "Even count: ${numbers.count { it % 2 == 0 }}" to the console, with a trailing newline
    println("Even count: ${numbers.count { it % 2 == 0 }}")
    // Print "Sum: ${numbers.sum()}" to the console, with a trailing newline
    println("Sum: ${numbers.sum()}")
    // Print "Sum of squares: ${numbers.sumBy { it * it }}" to the console, with a trailing newline
    println("Sum of squares: ${numbers.sumBy { it * it }}")
}

Grouping Elements

.groupBy { } किसी collection को दी गई function के result से keyed एक Map में partition करता है, हर key के तहत मेल खाने वाले सभी elements को साथ इकट्ठा करते हुए।

उदाहरण: Grouping Elements

markup

// Entry point: execution of the program starts here
fun main() {
    // Declare a read-only variable `words`, set to `listOf("apple", "banana", "avocado", "blueberry", "cherry")`
    val words = listOf("apple", "banana", "avocado", "blueberry", "cherry")
    // Declare a read-only variable `grouped`, set to `words.groupBy { it.first() }`
    val grouped = words.groupBy { it.first() }
    // Print `grouped` to the console, with a trailing newline
    println(grouped)
}

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Collection Operations क्या हैं

Sorting a Collection

Searching with find, any, all, none

Counting and Summing

Grouping Elements

Chapter Quiz — Complete all 7 topics to unlock

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